This invention discloses compositions consisting essentially of (1) reactive monomer, (2) multi-functional cross-linking agent, and at least (3) radiation sensitizer, (4) polymer binder, or (5) filler (with binder) that can be polymerized/cross-linked imagewise upon exposure to ionizing radiation, such as x-ray, electron beam, ion beam, and gamma-ray. This invention also discloses methods of using these compositions for microfabrication of ceramics, for stereolithography and as photoresist in x-ray, e-beam, and ion-beam lithography.
UV-VIS-IR-sensitive photopolymer compositions have been used extensively in many applications in the area of photolithography, graphic art, stereolithography, and printing and publishing. All of these applications require materials that can be polymerized imagewise; that is, the polymerization reaction is spatially confined to the region irradiated by the photons to retain the input image with good fidelity and spatial resolution. Because of the short penetration depth (in absorbing media) and scattering problems of optical photons, the use of relatively thin and transparent photopolymer films is usually required for these applications. Opaque medium is very problematic for this technology. For example, conventional photopolymer technology is not suitable for the patterning of ceramic materials.
These issues may be resolved by the development of useful x-ray sensitive photopolymers. X-ray has deeper penetration depth and, in the case of lithography, can achieve better spatial resolution than optical based technique. Unfortunately, no material has been developed that can be polymerized imagewise by a relatively low intensity x-ray beam within a reasonably short duration, as best known to the inventor. Organics have very low x-ray absorption coefficiency and polymerization reaction, it can be initiated by x-rays, tends to be inefficient and requires the use of either very long exposure time or high power x-ray source, such as synchrotron radiation. In addition, for applications requiring spatial resolution, the polymerization reaction has to be spatially confined to the irradiated region.
There are many potential applications for x-ray sensitive photopolymers if these materials are available. The microfabrication of ceramics and metals (for example, barrier rib fabrication for plasma flat panel display; S. W. Depp and W. E. Howard, Sci. Amer. 260,40 March 1993), stereolithography (3D-solid object modeling) (D. C. Neckers, Chemtech, October issue, p. 615, 1990) and photoresist for x-ray or e-beam or ion beam lithography (C. Grant Wilson in Introduction to Microlithography, eds. L. F. Thompson, C. G. Wilson, and M. J. Bowden, 1994, American Chemical Society, Chapter 3, p.139) are just a few examples. Other applications include x-ray contact microscopy (Applied Physics Letters, 72, 258 (1998) by A. C. Cefalas, P. Argitis, Z. Kollia, E. Sarantopoulou, T. W. Ford, A. D. Stead, A. Marranca, C. N. Danson, J. Knott, and D. Neely) and the fabrication of photonic crystals with photonic band gap properties (Science, 281, 802 (1998), by J. E. G. J. Wijnhoven and W. L. Vos).
The basic principles of initiating chemical reactions with ionization radiation can be found in xe2x80x9cRadiation Chemistryxe2x80x9d by A. J. Swallow, Wiley, 1973; and xe2x80x9cPulse Radiolysisxe2x80x9d by M. S. Matheson and L. M. Dorfman, MIT Press, 1969. Here ionization radiation is defined to include x-rays, xcex3-rays, neutrons, charged particles (ion beam), and electron beam. The irradiation of matters with ionization radiation can generate excited states; free radicals, cations, and anions. Under the proper conditions, these reactive species can initiate chemical reactions such as polymerization, cross-linking, and bond breaking.
Several patents disclose the use of gamma ray radiation for industrial applications. U.S. Pat. No. 3,950,238 (Apr. 13, 1976, R. J. Eldred) discloses an acrylonitrile-butadiene elastomer composition that can be cured by an electron beam. U.S. Pat. No. 4,004,997 (Jan. 25, 1977, Tsukamoto, Matsumura, Sano) discloses a process of curing a resin filled with powdery ferromagnetic substance using radioactive rays. U.S. Pat. No. 4,303,696 (Dec. 1, 1981, Brack) describes a method of curing a liquid prepolymer composition to form a waxy, release coating on a solid surface. U.S. Pat. No. 4,319,942 (Mar. 16, 1982, W. Brenner) discloses electron beam curing of adhesive compositions containing elastomers for building flocked composite structures. U.S. Pat. No. 4,353,961 (Oct. 12, 1982, Gotcher, Germeraad) discloses radiation cross-linking of fluorocarbon polymer to improve the mechanical strength. U.S. Pat. No. 4,547,204 (Oct. 15, 1985, Caul) discloses resin compositions, such as acrylated epoxy and phenolic resin, which can be cured by electron beam for coated abrasive application. U.S. Pat. No. 5,098,982 (Mar. 24, 1992, Long) discloses that the hardness of thermoplastic polyurethanes can be improved upon irradiation by electron beam. U.S. Pat. No. 5,037,667 (Aug. 6, 1991, Dubrow, Dittmer) discloses that certain organopolysiloxanes can be grafted to polymeric supports by the irradiation with electron beams. U.S. Pat. No. 5,332,769 (Jul. 26, 1994, Kakimoto, Eguchi, Kobayashi, Nishimoto, Iseki, Maruyama) discloses electron beam curing of adhesives for adhesion between a polyester film and a metal plate. J. Polym. Sci., XLIV, 117-127(1960) by B. Baysal, G. Adler, D. Ballantine, and P. Colombo discloses solid state polymerization of acrylamide initiated by gamma ray radiation to produce polyacrylamide. There was not enough solubility differentiation between the starting material and the product to allow spatially defined image formation. U.S. Pat. No. 4,115,339 (Sep. 19, 1978, by A. J. Restaino) discloses gamma ray initiated polymerization of nitrogen-containing vinyl monomers to form aqueous gels of water-soluble polymers. Both the starting material and the product are water-soluble so spatially defined image formation cannot be achieved.
All of the above patents and papers disclose methods or compositions used mostly for coating and adhesion applications under gamma ray radiation. The efficiency was generally low and the required spatial resolution for imaging applications was not demonstrated.
Recently, synchrotron radiation has been used to cross link polymethylmethacrylate for the precision machining of solid parts (Johnson, Milne, Siddons, Guckel, Klain, Synchrotron Radiation News, 9, 10 (1996)). The intensity of synchrotron radiation is roughly 1 million times higher than the common laboratory x-ray machines such as the ones used in this work. The extremely high intensity of the synchrotron radiation means the polymerization/cross-linking reactions can be initiated from almost any compositions (that is, it is non-discriminate). The high intensity also presents damage and heating problems with the mask that needs to be used for imaging applications. Because of the cost of the synchrotron machine and the limited availability, the use of synchrotron radiation is not practical. The compositions disclosed in this invention allow the use of commonly available, low intensity x-ray machine (or e-beam and gamma ray) to achieve spatially defined polymerization/cross-linking reactions.
U.S. Pat. No. 5,556,716 (Herron and Wang) discloses x-ray sensitive photo-conductive compositions for digital radiography applications. The compositions comprise of hybrids of organic polymers and inorganic nanoparticles. Unlike the materials disclosed in the present invention, x-ray generated electrons and holes in these photoconductors do not induce any chemical reactions; they are separated and transported out of the,film under high fields.
This invention discloses compositions that can be polymerized/cross-linked imagewise upon exposure to ionizing radiation such as x-ray, electron beam, ion beam, and gamma ray.
One of the disclosures of this invention is a composition, that can be polymerized/cross-linked imagewise by ionization radiation, consisting essentially of:
(A) from 10 to 90 weight percent of a reactive monomer having at least one amide functional group, said monomer selected from the group consisting of: 
xe2x80x83where R1, R2, R3, R4, and R5 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); aliphatic groups with amide or acrylamide substituent, and aliphatic groups with Rxe2x80x2Oxe2x80x94 substituent where Rxe2x80x2 represents aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and acetamide; 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and amino-substituted aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(B) from 10 to 90 weight percent of a multifunctional cross-linking agent, said cross-linking agent consists of a backbone with at least 2 functional groups, said backbone is selected from group consisting of:
(1) linear or branched aliphatic chains, xe2x80x94(CRH)nxe2x80x94, n=1-1000, where R represents an aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(2) ethylene glycol chains, xe2x80x94(CH2CH2O)nxe2x80x94 where n=1-1000;
(3) propylene glycol chains, xe2x80x94(CH(CH3)CH2O)nxe2x80x94 where n=1-1000;
(4) cyclohexyl; and
(5) isocyanurate, C3N3O3; and
xe2x80x83wherein the functional groups are selected from the group consisting of:
(a) acrylates, 
xe2x80x83where R1, R2, and R3 are selected from the group consisting of hydrogen and aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(b) carboxylic acid, xe2x80x94COOH;
(c) epoxides, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and
(d) vinyls, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and
(C) from 0.1 to 80 weight percent of an inorganic radiation sensitizer having a particle size in the range of 1 nanometer to 1000 nanometers, said radiation sensitizer is selected from the group consisting of VB-VIB semiconductors, VB-VIIB semiconductors, IIB-VIB semiconductors, IIB-VB semiconductors, IIIB-VB semiconductors, IIIB-VIB semiconductors, IB-VIB semiconductors, and IVB-VIIB semiconductors.
This invention also discloses a composition, that can be polymerized/cross-linked imagewise by ionization radiation, consisting essentially of:
(A) from 10 to 90 weight percent of a reactive monomer having at least one amide functional group,.said monomer selected from the group consisting of: 
xe2x80x83where R1, R2, R3, R4, and R5 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); aliphatic groups with amide or acrylamide substituent, and aliphatic groups with Rxe2x80x2Oxe2x80x94 substituent where Rxe2x80x2 represents aliphatic group, CnH2n+1 and CnH2xe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic a groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and acetamide; 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and amino-substituted aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(B) from 10 to 90 weight percent of a multifunctional cross-linking agent, said cross-linking agent consists of a backbone with at least 2 functional groups, said backbone is selected from the group consisting of:
(1) linear or branched aliphatic chains, xe2x80x94(CRH)nxe2x80x94, n=1-1000, where R represents an aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(2) ethylene glycol chains, xe2x80x94(CH2CH2O)nxe2x80x94 where n=1-1000;
(3) propylene glycol chains, xe2x80x94(CH(CH3)CH2O)nxe2x80x94 where n=1-1000;
(4) cyclohexyl; and
(5) isocyanurate, C3N3O3; and
xe2x80x83wherein the functional groups are selected from the group consisting of:
(a) acrylates, 
xe2x80x83where R1, R2, and R3 are selected from the group consisting of hydrogen and aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(b) carboxylic acid, xe2x80x94COOH;
(c) epoxides, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and
(d) vinyls, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(C) from 0.1 to 80 weight percent of an inorganic radiation sensitizer having a particle size in the range of 1 nanometer to 1000 nanometers, said radiation sensitizer is selected from the group consisting of VB-VIB semiconductors, VB-VIIB semiconductors, IIB-VIB semiconductors, IIB-VB semiconductors, IIIB-VB semiconductors, IIIB-VIB semiconductors, IB-VIB semiconductors, and IVB-VIIB semiconductors; and
(D) 5 to 90 weight percent of a polymer.
Additionally, this invention discloses a composition, that can be polymerized/cross-linked imagewise by ionization radiation, consisting essentially of:
(A) from 10 to 90 weight percent of a reactive monomer having at least one amide functional group, said monomer selected from the group consisting of: 
xe2x80x83where R1, R2, R3, R4 and R5 are selected from the group consisting of hydrogen; aliphatic groups CnH2H+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); aliphatic groups with amide or acrylamide substituent, and aliphatic groups with Rxe2x80x2Oxe2x80x94 substituent where Rxe2x80x2 represents aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and acetamide; 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and amino-substituted aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(B) from 10 to 90 weight percent of a multifunctional cross-linking agent, said cross-linking agent consists of a backbone with at least 2 functional groups, said backbone is selected from the group consisting of:
(1) linear or branched aliphatic chains, xe2x80x94(CRH)nxe2x80x94, n=1-1000, where R represents an aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(2) ethylene glycol chains, xe2x80x94(CH2CH2O)nxe2x80x94 where n=1-1000;
(3) propylene glycol chains, xe2x80x94(CH(CH3)CH2O)nxe2x80x94 where n=1-1000;
(4) cyclohexyl; and
(5) isocyanurate, C3N3O3; and
xe2x80x83wherein the functional groups are selected from the group consisting of:
(a) acrylates, 
xe2x80x83where R1, R2, and R3 are selected from the group consisting of hydrogen and aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(b) carboxylic acid, xe2x80x94COOH;
(c) epoxides, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and
(d) vinyls, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(C) from 0.1 to 80 weight percent of an inorganic radiation sensitizer having a particle size in the range of 1 nanometer to 1000 nanometers, said radiation sensitizer is selected from the group consisting of VB-VIB semiconductors, VB-VIIB semiconductors, IIB-VIB semiconductors, IIB-VB semiconductors, IIIB-VB semiconductors, IIIB-VIB semiconductors, IB-VIB semiconductors, and IVB-VIIB semiconductors;
(D) 5 to 90 weight percent of a polymer binder; and
(E) 5 to 90 weight percent of metallic particle or ceramic oxide fillers, said metallic filler is selected from group consisting of Al, Ti, V, Cu, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, and Sb; said oxide filler is selected from the group consisting of Al, Ti, V, Cu, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, Sb, Ta, W, and Si.
Another disclosure of this invention is a composition that can be polymerized/cross-linked imagewise by ionization radiation consisting essentially of:
(A) from 10 to 90 weight percent of a reactive monomer having at least one amide functional group, said monomer selected from the group consisting of: 
xe2x80x83where R1, R2, R3, R4, and R5 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); aliphatic groups with amide or acrylamide substituent, and aliphatic groups with Rxe2x80x2Oxe2x80x94 substituent where Rxe2x80x2 represents aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and acetamide; 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2n+1 (n=1 to 20); and unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and amino-substituted aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(B) from 10 to 90 weight percent of a multifunctional cross-linking agent, said cross-linking agent consists of a backbone with at least 2 functional groups, said backbone is selected from the group consisting of:
(1) linear or branched aliphatic chains, xe2x80x94(CRH)nxe2x80x94, n=1-1000, where R represents an aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(2) ethylene glycol chains, xe2x80x94(CH2CH2O)nxe2x80x94 where n=1-1000;
(3) propylene glycol chains, xe2x80x94(CH(CH3)CH2O)nxe2x80x94 where n=1-1000;
(4) cyclohexyl; and
(5) isocyanurate, C3N3O3; and
xe2x80x83wherein the functional groups are selected from the group consisting of:
(a) acrylates, 
xe2x80x83where R1, R2, and R3 are selected from the group consisting of hydrogen and aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(b) carboxylic acid, xe2x80x94COOH;
(c) epoxides, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and
(d) vinyls, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and
(C) 5 to 90 weight percent of a polymer binder.
A further disclosure of this invention is a composition, that can be polymerized/cross-linked imagewise by ionization radiation, consisting essentially of:
(A) from 10 to 90 weight percent of a reactive monomer having at least one amide functional group, said monomer selected from the group consisting of: 
xe2x80x83where R1, R2, R3, R4, and R5 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); aliphatic groups with amide or acrylamide substituent, and aliphatic groups with Rxe2x80x2Oxe2x80x94 substituent where Rxe2x80x2 represents aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and acetamide; 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); and unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); 
xe2x80x83where R1 and R2 are selected from the group consisting of hydrogen; aliphatic groups CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20); unsaturated aliphatic groups CnH2nxe2x88x921 (n=1 to 20); and amino-substituted aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(B) from 10 to 90 weight percent of a multifunctional cross-linking agent, said cross-linking agent consists of a backbone with at least 2 functional groups, said backbone is selected from the group consisting of:
(1) linear or branched aliphatic chains, xe2x80x94(CRH)nxe2x80x94, n=1-1000, where R represents an aliphatic group, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(2) ethylene glycol chains, xe2x80x94(CH2CH2O)nxe2x80x94 where n=1-1000;
(3) propylene glycol chains, xe2x80x94(CH(CH3)CH2O)nxe2x80x94 where n=1-1000;
(4) cyclohexyl; and
(5) isocyanurate, C3N3O3; and wherein the functional groups are selected from the group consisting of:
(a) acrylates, 
xe2x80x83where R1, R2, and R3 are selected from the group consisting of hydrogen and aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(b) carboxylic acid, xe2x80x94COOH;
(c) epoxides, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2xe2x88x921 (n=1 to 20); and
(d) vinyls, 
xe2x80x83where R1, R2, and R3 are selected from: hydrogen or aliphatic groups, CnH2n+1 and CnH2nxe2x88x921 (n=1 to 20);
(C) 5 to 90 weight percent of a polymer binder; and
(D) 5 to 90 weight percent of metallic or oxide fillers, said metallic filler is selected from group consisting of Al, Ti, V, Cu, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, and Sb; said oxide filler is selected from the group consisting of Al, Ti, V, Cu, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, In, Sb, Ta, W, and Si.
This invention also discloses methods to use these compositions for microfabrication of ceramics, for stereolithography and as photoresists in x-ray, e-beam, and ion-beam lithography. Disclosed in this invention is a method of microfabricating ceramic or metal patterns on a solid substrate using ionization radiation comprising the steps of:
(i) mixing together a composition consisting essentially of a reactive monomer, a multi-functional cross-linking agent and filler; said mixing process optionally carried out either by heating the composition until melted or by dissolving components in a common solvent;
optionally, in the presence of binder; and
optionally, in the presence of a radiation sensitizer;
(ii) casting the composition on a solid substrate to form a film of desired thickness;
(iii) irradiating the film with ionization radiation through a mask to form a polymerized/cross-linked image;
(iv) developing the polymerized/cross-linked image by rinsing the irradiated film in a solvent to remove unirradiated composition; and
(v) sintering the polymerized/cross-linked image in microfabricated ceramics or metal patterns.
This invention also discloses a method of performing lithography on a semiconductor surface using ionization radiation, comprising the steps of:
(i) mixing a composition consisting essentially of a reactive monomer and a multi-functional cross-linking agent together, optionally by
(a) heating the composition until melted; or
(b) by dissolving in a common solvent;
optionally, in the presence of a polymer binder; and
optionally, in the presence of a radiation sensitizer;
(ii) casting the composition on a solid substrate to form a film of desired thickness;
(iii) irradiating the film with ionizing radiation through a mask to form a polymerized/cross-linked image; and
(iv) developing the polymerized/cross-linked image by rinsing the irradiated film in a solvent to remove unirradiated composition.
A further method disclosed in this invention is a method of forming a three-dimensional solid object of polymers, ceramics, or metals using ionization radiation, comprising the steps of:
(i) mixing together a composition consisting essentially of a reactive monomer, a multi-functional cross-linking agent, and a polymer binder, said mixing process optionally done by dissolving in a common solvent or by pouring the composition into a container with a target substrate immersed in it;
optionally, in the presence of a radiation sensitizer; and
optionally, in the presence of a metallic or oxide filler;
(ii) irradiating the composition with ionization radiation through a mask or a focused source of ionization radiation to deposit a layer of material on the targeted substrate;
(iii) stepping back the substrate and irradiating the substrate;
(iv) repeating the step of stepping back the substrate and irradiating the substrate until a desired three-dimensional solid object is formed; and
optionally, treating the solid object post-irradiation.